Weight-transferring vehicle coupling or hitch structure



Jan. 11, 1949. L. R. siMMoNs WEIGHT TRANSFERRING VEHICLE GOUPLING 0RHITCH STRUCTURE Filed Jan. 15, 1 944 Patented Jan. 11, 1949WEIGHT-TRANSFERRING VEHICLE v COUPLING OR HITCI-I STRUCTURE Lovel R.Simmons, Jackson, Miss. l Application January 15, 1944, Serial No.'518,336 1 claim. (o1. 28o-33.44)

1 This invention relates to hitches operable between a propellingvehicle and a vehicle prol,pelled thereby, for transferringtraction-augmenting weight from the propelled to the propelling vehicle,and, more particularly, the invention concerns a fluid-energized hitchof this character and a source of energizing fluid controlled to causesaid hitch to make adjustment for changes in relative elevations of thevehicles (and thereby diminish fluctuations in the transferred Weight)Awhile they are traversing an irregular course.

The advantages of a weight-transferring hitch between propelling andpropelled vehicles are fully described in my copending applicationSerial No. 413,550, now Patent No. 2,382,449, dated August A14, 1945. Inexplaining the present invention it will suiiice to refer to theparamount advantage of such a hitch, namely, the practical adaptation ofa general purpose relatively lightweight traction vehicle for propellinga heavy normally self-supporting vehicle under condivehicle from rest`or propelling it from a depression or over a hummock or up any steepineline. After the necessity for the transferred weight has passed, thehitch is relaxed to permit the propelled vehicle to support itself onits own front and back wheels.

When employing a traction vehicle `in the aforesaid manner because of itbeing insufficiently rugged (and correspondingly less costly)l to peremanently carry part of the propelled vehicle, it is important to guardagainst sudden excessive load increases imposed onto the tractionvehicle through the hitch structure while the latter is transferringweight. For instance, while the vehicles are traversing an irregularcourse with the hitch in weight-transferring operation, should the hitch-be rigid and the tractor en counter a hummock or the propelledvehiclepass over the brink of a depression there would be a suddenenormous increase in the transferred weight, tantamount to a severeforce impact, incurring destructive wrenching of the tractor. An objectof this invention is to provide a hitch together with a control thereforwhich will prevent excessive increase in such traction force limposed onthetractor.

`A further object is the provision of al weighttransferringhitchjcooperable with a control to cause continued application of thetraction force in virtually undimlnished amount under circumstances as`where the tractor should drop over the brink ofva depression in thecourse of travel or where the propelled vehicle should rise onto ahummock. It follows therefore that the objects of this invention includethe provision of an adjustable hitch' andcontrol cooperable to transmitav desired tractionjimproving pressure from the propelled vehicle ontothe tractor while preventing inordinate fluctuations in such pressurewhile ythe vehicles proceed over al rough uneven path.`

A further object is the provision'of a weight-` transferring hitchhavingan'expansible chamber of which the volume is correlated withadjust-- ments of the hitch to accommodate changes in elevation of thevehicles, in combination with a supply of fluidinter-communicative withsaid 'e chamber to inject fluid thereinto or .receive fluid tionsrequiring increased traction weight on the therefrom to facilitate theaforesaid adjustment of the hitch while causing it to transmit a desiredamount of weight irrespective of the adjustment.

A further object is the provision, inv a hitch and control as the above,of acontrol fluid source Y selectively conditionable to operate atA willto energize the hitch for transferring `weight or to relax the hitch sono Weight is transferred.

Still a further object is the vprovision of a hitch and controlaccording to the next preceding object, wherein ,the iiuid source isregulatable to predetermine the pressure of fluid therein andconsequently the amount 4of weight transferred `when the source isoperated, whereby the apparatus is capable of being set by a skilledperson and used by one not necessarily skilled Vor trained.

l When apparatus of the present kind is used, the

operator need only set a control member when encountering adversetraction conditions whereupon, so long as the control member remainsset.

the apparatus will automatically function to transfer the proper amountof weight in a man ner absorbing shocks caused by unevennessof thecourse. l

These and other objects encompassed by and inherent in the inventionwill be more readily understood from the ensuing descriptionand theannexed drawings,wherein:

Fig. 1 is a side elevational View of a tractor and an earth haulingvehicle` coupled thereto by a weight transferring coupling or hitchstructure controlled in the ,amount of weight transferred thereby fromthepropelled vehicle onto the,- trac-` 3 tor by a fluid supply means orsource constructed according to the principles of the present invention:

Fig. 2 is a View, partly diagrammatic, illustrating in cross section thevalves employed in the uid supply system .and their connections withcomponent parts of the iiuid circulatory system.v *j i v,

Withcontinue'dlreference to the Adrawings,A the tractor l0 is shownconnected to an earth hauling vehicle Il by a weight transferring hitch.or coupling structure l2.

The tractor has the usual fron-t lsteeringrtruck I3 including steerablewheels i4 ofwhich-one is shown in the drawing. The tractorialsohas aypair of traction wheels luponopposite sides of the tractor body l5 andofwhich'wheels theone nearest the observer has been removed for. bet- 4extend through aligned holes in said projections and in laterally spacedarms 5'! at the back end of the drawbar. The pivot pins 56 permit thedrawbar 54 to pivot within a vertical plane while constraining saiddrawbar and the front axle 29 for unitary pivotal movement about thevertical pivot axis for said axle intersecting the support pedestal 28.,.Thus the pins 55 together with the pivotal connection of .said axle 29with the pedestalr 28 provide a universally articulate connection.between the drawbar and the propelled vehicle frame and enables thedrawbar to impart steering movement to the front wheels 3i when swung y`horizontally while vfacilitating upward or downward swinging movementof the drawbar. A universally articulate connection is provided betweenthe frontend of the drawbar by a clevis pin 58, a clevis a C-couplingmember 5l and a ter illustrating the connections of the hitch verticalpivot pin 62 connecting said clevis with structure.rwiththe, rearV5 axlehousing liof the u the, coupling member tl. Strap means E3 is tractor.,"Iherusual' driving axles i2. extending bolted to the coupling plates 53for connecting the .Y moppositelylwithin, the rear=axle .housing aredrivcoupling member 6l withthe tractor.

,inglyl connectedjwith, tha.reariv traction wheels. "When it is desiredto increase the traction of ,Inflated rubber tires I9 and 2l` arerespectively the tractor tires 2l this can be done by introducupon`thafront `vvheelsand.rear -wheels of the g5. ing uidlpreferably oil)into the chamber 45 of tractor. n thedistensible device 42 undersufficient pres- ."The propelled vehicle comprises 4a frame 22 I sure todistend the device by forcing the plunger which supports an, earthhauling bodyl23 orthe 'M upwardly. Meanwhile the drawbar 54 prelike. YPedestals 24. depend from the frame 22 at `vents separation of thevehicles whereby an up- V-opposite Sides of .the vbody' 23 for restingupon a 5o ward component'of force is imparted to the cou-4rearf`rxl`e125 supported. at`,opposite ends by wheels 2,6.providedwithinflated rubber tires 2.v At the front. of the frame'22there isla depending pedestal'28 having a suitable fth'wheel connection30 ,with an.intermediater portion of an axle 29 to permit pivotal'.movement 'ofithis axle about a verticallaxis. "'.Eachjend of the axle.'29 carries a `wheel 3| on".which` thereisanrinated tire' 32. Acouplingpede'stal'SSrigidly connected withthe plingpedestal 33 bythe' plunger 44in suiiicient n, magnitude for lifting or partially lifting the frontendof the propelled vehicle. Part of the .weightthus relieved from thetires 32 of the propellecl" vehicle is 'transferred onto the rear tires2l' of 'suchwehicle and part of the weight is 'transferredto thetraction tires 2l of the tractor throughthe hitch orcoupling structurel2.

' Whensthedevice 42 is distended as aforesaid .L vfrarnej22 projectsupwardly therefrom andhas a .brace connection' "3,4 ,with the .vehiclebody 23. i JThis couplingrp'edestal 33 hasvertically spaced; Vvapertured ears 35 and 35Aforjthe reception of a pins. 56 and 58 at itsrear rand forward ends. y. pivot pi-n 311havinga collar !38V.pivotablythereon. 'The pivot `pins 3l and 49 in the universal joints'il.Spacedfapartjapertured ears39` projecting for- 45 at the upper andlower ends of the device 112 wardly from the collar 38 receive ahorizontally t facilitate turning ofthe tractor relatively to theextendingpivotpin- 4I/whichrconnectstheupper .vehicle while swinging thedevice i12 laterally. A end of a distensiblecou'pling device 42therewith. i similar function is performed by the pivot pin `Thisdeviceiconsists of a hollow cylinder'LliSclosed 62 in the universaljoint at the forward end of at'its'lowerend.andfopenatitsRipper*end anda 50" the dravvbar 515 and the'aforesaid vertical axispiston-likeplunger'dprojecting ntothe, upper pivot for the propelledvehicle front axle 29. kend" of said cylinder."i'`husthe members 43landThat is,v the pivot pin 62 permits' the tractor to 54' cooperate' to'forman expansible and conturn relatively to the drawbar 54Yand theaforetractibleichamber'45-within the lower-end ofthe said vertical axispivotv permits the tractor to cylinder 43. i swing the drawbar 54 forswinging the front "-'A universally articulatableconnection forconwheelsof the trailer for steering the same. nectingthelowerflendlof'thedistensible'device 42 Typical weights supported by the various pairswith the tractonincludesran apertureclear 46 off'front and back tiresupon the tractor and v-"on"the lowerfend of-YthefcylinderAS, a yoke 4'!propelled vehicle are indicated by the numerical havingaperturedears vt8straddling the vear 46, 00' amountsA written'immediately below suchtires. Va' pivot pingconnecting saidy ears; and diverging The uppermostamounts writtenbelow the tires -leg-s'lton'e being shown inFig.1')-pivotally conindicate weightsr supported by the f associatedfnectedby pins''52-'withrespectiveflaterally spaced -\-pair oftiresffwhenhthe'hitch structure is replates53^suitably attached tothatportion of the laxedpthat is,` when there is no fluid pressurefrerearlaxlefffhousing which' enclosesthensual `dif Gi within the`chamber 45. The lowermost amounts ferential gear unit (not shown)through' which written below the pairs of tires signify the typicalvthetractoriaxlesvlB'are vdriven: Thepin il at @weights supportedthereby when uid is injected iii-the:v upper e'ndof' theffdiste'nsibledevice' LMythe "into" the chamber 45. In the example given itfVcollarP38-and 'the' pir31fprovide a^universa1ly will be seen that thetraction tires of. the tractor articulate connectionvforthe=upper end ofthis. carry only-7,240 pounds when the hitch or couifl'devicezwith thecoupling'pedestal' 33. pling structure is relaxed and that this weightis Adrawband is-connec`ted tothe frontaxle 29 increased to 17,020 poundswhen exigencies arise ."f-"oilf-lthe propelledr-vehicle` by means'oflaterally making itf desirable to transfer weight from the .,:sfspacedprojections `liconnected rigidly with such pro1 el1ed vehicleontothetractorror increasing `v-rfiaxleV andhorizontally,disposedpivotpinslt which its traction. Normally-the entireweight ofthe pivoting thereof is incurred about the pivot pins 4i and 52at its upper and lower ends and pivoting of the drawbar 54 is incurredabout the pivot .mounted upon the sideof its engine a pump loadedpropelled vehicle will be supported upon its own two pairs of front andback wheels, and even when weight is transferred by the hitch structurefor increasing the traction of lthe tractor it is desirable that part ofthe weight of the propelled vehicle should remain upon its front tiresto improve the stability of the vehicle.r But even when leaving adequateweight upon the front tires of the propelled vehicle the weighttransferable onto the tractor is immensev and should be applied theretoevenly, that is, without sudden impact and only for relativeshortduration emergency periods so as not to wrench the body of thetractor and strain or unduly shorten the life of the tractor tires. Whenthe uid pressure within the expansible chamber 45 of the hitch structureis properly controlled by apparatus now to be described said vhitchstructure can adjust itself while energized for transmitting a desiredamount of lweight onto the tractor so as not to inordinately fluctuatethe amount of such transferred weight while the vehicles traverse anuneven course such as one having a series of depressions and/orhummocks. For instance, if the hitch structure were crease the weighttransferred onto the tractor while perhaps raising the front wheelsofthe trailing vehicle completely off of they ground. This sudden increaseof transferred weight onto the tractor would be at a speed at which theincreased weight would be tantamount to a force impact. It is thepurpose of the fluid control apparatus now to be described to avoid thiskind of punishment to thetractor.

Referring again to the tractorr there is shown.

constantly driven from the engine. This pump may be a gear pump or anykind of positive delivery pump. Also upon the engine there is mounted areservoir R. for a quantity of the cir-a culated fluid ,-(preferablyoil), a manually operated valve V and a pressure relief valve PV.

Normally the valve V will bein the position 6 l constrained forrotation. In this manner the valve member 69 is rotatedcounter-clockwise for moving the channel 1|` out of registry with any ofthe vcasing -ports while transferringthe channel 12 into registry withthe porti 66 and leaving the channel 11 in communicative registry withthe conduit 15. The Aby-pass condition of the fluid circuit will be thusterminated and the output Afrom the vpump will be directed through theconduit 65, port66, channel 12,1channel 11, port 16 and the conduit 15into the hitchstructure chamber 45. The pressure attained within thechamber 45 is'determined by selectively setting'the pressure reliefvalve PV.4 Upon the attainment vof acertain pressure in the chamber 45the fluid-f within the conduit 15 fed. downwardly through the lower leg83 of a T-coupling 84 will Aforce avball 85 from its seat 86,4permitting the fluid to escape into the pressure relief valve chamber81and thence through a conduit88 back into fthe reservoir.

' is made preferably while the vehicles are at rest #conditions yupon alevel course vand while the tractor engine is Vdriving the pump at aspeed corresponding to that at which the tractor engine will normally bedriven under conditions requiring the tractor to transmitsufiicientforce toits traction wheels for propelling the, loaded vehicle H underadverse This willfbe a. fast engine speed. While the engine is runningat this fast speed the control lever 19` will -be Ipushed forwardly for`adjusting the valve rotor'l to the above described operated position inwhich' its channel 12 is in illustrated in Fig. 2 so that-oiltaken fromthey reservoir R by the pump through a conduit rtill and delivered fromthe pump through a conduit fluid returns to the reservoir R through arotor` passage 1'2, a casing port 13 and a vconduit 14.

' Thus there is free circulation of the uidbyv the pump at a low by-passpressure. A hose orjconduit 15 communicating at its rear end with thechamber 45 has a breather connection with the reservoir R through acasing port 16, valve rotor passage 11, valve rotor chamber B8, valverotor passage 12, casing port 13 and the conduit -14 so that at thistime the chamber 45 will be deflated and the hitch structure relaxed.

When it is desired to energize thehitch structure for transferringweight onto the'tractor an operator upon the tractor seat 18 will pushforwardly upon a lever 19 and thereby pull backwardly upon a link 8| andthe uppergzendof a registry withy the port"66. lA screw plug 89 in Ilupwardly. An operator having knowledge of the maximum amount of weightdesired to be transferred onto the tractor from the vehicle Il in anemergency requiring increased traction, will then screw the valve plug89 upwardly and thereby correspondingly increase the resistancer ofiiuidby-pass and the magnitude of iiuid pressure within the chamber 45. Whenthis uid pressure reaches the magnitude which expands the chamber 45 totake. a portion of the flex out of the front tires of the vehicle Ilincident to applying the desired maximum Weight onto the tractor. thevalve PV will be properly adjusted and will be left in that adjustmentLater when the vehicles are employed as upon a construction job where aninexperienced operator may be upon the tractor, this operator can whenencountering conditions requiring additional traction, simply pushforwardly upon the lever 19 and thereby introduce fluid into the hitchchamber 45 to energize the hitch structure whereby the predeterminedamount of weight will be transferred onto the tractor. All during theemergency while additional traction force is being applied onto thetractor by the hitch structure the constantly driven pump P will bedelivering fluid and the entire output of the pump will y be passingthrough the valve PV back to the reservoir for re-circulation. Thusthere is a constant supply of pressure iluid in pressure transferringrelation with the expansible and contractible chamber 45 so that, forexample, should the back :wheels offthe=tractor dlropinto a-shalimrv=ho1e`- or depression :fluid-still aatithe: desired pressure:Will .be availableand injected into-:thechamber 45 for maintaining' thefhitch.- structure' yenergized for continued transfer lot-theigdesiredul amount of i Weight `onto the tractoriwhileftheexpansiblede` vvice i2 is increased in length Subsequently upon "the tractionWheelsof then` tractor advancing upwardly out ofvthedepressionthepressure relief valve PV willifprevent -anundesirable ypressure surgein.the .chamber (anlthe' attendant force impact ontothe tractor) bypermitting ysaid chamber` to' .contract incident toshortening -ofthefexpansibie device 42;

' Upon the'rear Wheels oft-the tractoriencountering and passing overalhummock'transfer of iiuid between thechamber 45 and the uid sourceincluding the reservoir` and pump uponthe tractor vation.

The hitch structure ,l is inherently adjustable by the -rnovementof theplunger 44 inthe cylinder 43 for permitting relative changes'in theelevation of' the vehicles 'ands' when the hitch structure is energizedby thefintroduction of uid under pressure into the chamber 45 Vto obtainwhat may he regarded as a normal adjustment of the hitch structureincident to the transfer of a desired amount of force onto the tractorwhile the vehicles are upon a level course, the active source of fluidin fluid transfer relation with the chambertiEa is operable subsequentto the reception of fluid rornthe contracted chamber or subsequent totheinjection of fluid into said chamber when it is expanded, torespectively inject'fiuid into saidchamber and receive uid froml saidychamber for reestahlishing said. normal adjustmentl upon the vehiclesagain encountering a level course. y

Having thus described my invention with reference to the. annexeddrawings. withvtheyiew. of

`cleariy iilustratingthe same, I claimt' An apparatus `forv couplingatractor .toa vehicle to be propelledtherebyand self-supported upon vaplurality @ground-engaging parts; the cornbination of a hitch structureadjustable to accommodate .variation in ,the .elevations of .saidtractorand 4vehicle Whiletheytraverse.annneven course,

Ysaid structure; including f-.achamber-Which exjpands. and contractsyattendant'to such A.adjustment l and-.i which,` chamber fis.:receivable-.of I fluid underfpres-sureftorenergizethe structure for4transfIerringfweightffrom :said .vehicleVV onto the tractorinan;amount-constituting a function of thepressure ofgithe- 1iuid;.Aandsaid hitch structure ffbeing universallyffarticulately. .connectedVbetween .said tractor-` and. tvehicle"-.whereby stability oi: theY ve-10 Yhic1e.-withf frcspectqto .i tippingfsidewise would be diminished-:ifatheehitchshouldvlift the l.Vehicle .fsufcientlyto terminatecontact ofany ground- .--fengagin-g partthereot'with the-ground; and iiuid supplylmeans -for rdeliveringffenergizing fluidintoI-.ther-chamberwhen;itexpands and for receiving'gflu-id:irornfsaidcharnber v vhenitcontractstomodulatezgthecpressuregof ztluidftlfierein pursuant to adjustments'ofsaid structure, said yfluid supply ,meanstincluding .aaluidreservoir, a constant delli-very pump4 driven fromy the tractor towithdraw iuidi from#the.lreservoir, a conduit. connecting said:v chamberi, with` the pump outlet, Ipressure relief valve `Ifneansconnectedbetween; thehpump .ontletwandfthe reservoir-V and also betweensaid chamber and lthe, freservoir, .said pressure relief ,.valvc.-means-:being'settabl-euto .limit .the pressure orffluidi .delivered`by\the..1;iurn1:i .and contained in F:said .chamber to :-a,.value=.insufcient to energize fthe, structure'. forVraisingany` of theground-en- 4gagingtparts,ofcthe vehicleifrom the ground,-v and amanually-controlled. valve` means selectively s etl.tabiein 'anadjustment ,establishing concurrent communication ofqsaidichamberend of`the pump with thereservoirindependentlyA of the. pressure reliefValve.. means. .and .i instantaneously settable in anotherxadjustmentreestablishing. communifea-tion of i thef.pumpoutlet...and of .said.chamber .with the reservoir only through .the pressure re- .lief valveJneans.

LOVEL R.. SIMMONS.

` "REFERENCES .CITED The following references :are of Vvrecord in the"fue v/of'fthis'patent;

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